A technique disclosed in this specification relates to a solid-state imaging device used in an imaging apparatus such as an electronic endoscope.
In recent years, electronic endoscopes which incorporate solid-state imaging devices are widely used. Electric endoscopes are used such as for examinations and minimally invasive surgery in the medical field, and a reduction in diameters of the electric endoscopes is demanded to reduce patients' discomfort and expedite post-operation recovery.
Japanese Laid-Open Patent Application Publication No. 11-32982 discloses an endoscope including a solid-state imaging device in which an imaging area provided with CCDs (Charge Coupling Devices) and peripheral circuits exist on one chip (first conventional technique). The provision of the imaging area and peripheral circuits on the same chip reduces the number of signal lines at an insertion portion of the endoscope, thereby making it possible to reduce the diameter of the distal end of the endoscope.
Japanese Laid-Open Patent Application Publication No. 63-303580 discloses an endoscope in which a CCD solid-state imaging device is provided at an insertion portion of the endoscope (second conventional technique). In the conventional endoscope, the optical axis of light incident from outside is bent to a right angle by a prism placed on an imaging area of the solid-state imaging device, and the light hits the imaging area vertically. The solid-state imaging device is positioned such that the substrate surface of the solid-state imaging device is parallel to the axis of the endoscope. This structure makes it possible to reduce the diameter of the insertion portion of the endoscope more than the structure in which the solid-state imaging device is positioned such that the substrate surface of the solid-state imaging device is perpendicular to the axis of the endoscope.